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The other day I noticed my seatbelt warning light no longer comes on. Most likely this is attributual to a broken seat sensor or possibly a defective cable.
My question is, how important is this feature? If only for the warning light, I won't bother fixing it, but if it bars me from other comforts, I might give fixing it a bash.
Without knowing the year and model of your Jaguar we can only guess at appropriate replies to your questions. Please let us know. Better yet, please use your User Control Panel to add the year, model and engine details to your signature line so others don't have to ask.
Without knowing the year and model of your Jaguar we can only guess at appropriate replies to your questions. Please let us know. Better yet, please use your User Control Panel to add the year, model and engine details to your signature line so others don't have to ask.
Cheers,
Don
HI Don,
The car is a 1993 Daimler Double Six. It has the 6 litre v12 engine if that helps.
Our '93 did not have sensors in the seat cushions, but it did have switches in the seat belt latches or buckles that connect directly to the Central Microprocessor (CPU), which manages functions such as central locking, interior lighting, turn signals, starting, windshield wipers, seat belt warnings, etc.
Since a '93 has only one airbag, in the steering wheel, and the airbag is mechanically activated, I don't think you have to worry that the airbag is disabled if the seat belt warning lamp doesn't come on.
You might try inserting the seat belt tongue into the latch and wiggling it around or inserting and releasing the tongue multiple times to see if the warning lamp will come on. It's quite possible that the bulb in the instrument cluster (IC) has burned out or its terminals are corroded.
Our '93 did not have sensors in the seat cushions, but it did have switches in the seat belt latches or buckles that connect directly to the Central Microprocessor (CPU), which manages functions such as central locking, interior lighting, turn signals, starting, windshield wipers, seat belt warnings, etc.
Since a '93 has only one airbag, in the steering wheel, and the airbag is mechanically activated, I don't think you have to worry that the airbag is disabled if the seat belt warning lamp doesn't come on.
You might try inserting the seat belt tongue into the latch and wiggling it around or inserting and releasing the tongue multiple times to see if the warning lamp will come on. It's quite possible that the bulb in the instrument cluster (IC) has burned out or its terminals are corroded.
Thanks for the speedy and thorough reply.
The bulb itself is fine as it briefly lights up with all the others before starting the engine.
The airbag is one concern, the delay on the interior lights going off a second and the heated sets a third, as neither of the latter seem to work. But those wont be related issues then?
Our '93 did not have sensors in the seat cushions, but it did have switches in the seat belt latches or buckles that connect directly to the Central Microprocessor (CPU), which manages functions such as central locking, interior lighting, turn signals, starting, windshield wipers, seat belt warnings, etc.
Since a '93 has only one airbag, in the steering wheel, and the airbag is mechanically activated, I don't think you have to worry that the airbag is disabled if the seat belt warning lamp doesn't come on.
You might try inserting the seat belt tongue into the latch and wiggling it around or inserting and releasing the tongue multiple times to see if the warning lamp will come on. It's quite possible that the bulb in the instrument cluster (IC) has burned out or its terminals are corroded.
Reflecting on your answer, I am not sure it is correct.
The light works for the driver and passenger seatbelt. But if there's no passenger it doesn't stay on all the time. So it knows if there is a passenger and then the light works accordingly (tested this). So there must be a sensor of sorts.
Would this sensor also influence the workings of the heated seats and interior light switch off delay? I am asking as neither of these work on the drivers side.
Reflecting on your answer, I am not sure it is correct.
The light works for the driver and passenger seatbelt. But if there's no passenger it doesn't stay on all the time. So it knows if there is a passenger and then the light works accordingly (tested this). So there must be a sensor of sorts.
Hi Ramses,
The reason I know our '93 XJ40 did not have a passenger seat sensor is that I took the lower cushion apart to repair the leather before redyeing it. There was a seat heater coil but no occupant sensor.
I don't know if you've studied the 1993-94 Electrical Guide I provided the link for, but as far as I have been able to determine, it does not show seat occupant sensors for any of the seats, either in the seat cushions or in the the center roof console.
However, a thought just occurred to me: Is it possible that your car is not an XJ81 (12-cylinder car based on the XJ40), but rather an X305 (based on the X300)? In the U.S., the X300/X305 were introduced for the 1995 model year, but in Europe they were introduced earlier. If yours is one of these, the documents at the links below might be helpful:
first of all, the car is definately an xj81, so the 93-94 v12 model.
Picture here:
A quote from the 91 owners manual states:
"A 20 second delay will be activated when all the doors are closed and either front seat is occupied. The interior lights will extinguish immediately when the engine is started."
So this implies to me the car has a way of knowing whether or not a seat is occupied.
That's great information! I looked up that part number at jaguarclassicparts.com and according to the listings there, that sensor was used on XJ40s from 1988 to mid-1992, but not on the 1993 and later cars, which began at VIN 674581. I wonder if the XJ81 continued to use the sensors? Here are two snips from the part listing:
If there is a seat sensor I think it must be in the seat back, not in the bottom cushion.
AFAIK on both the 94 MY Sovereign and VDP/Daimler trim levels the seat squab can be removed by taking out the front apron screw and lifting up and forward. Unless I'm mistaken there are no electrical pigtails attached to the squabs?
Been a while since I took out the seats but have no recollection of any electrical disconnects needed to remove the lower cushion.
Just a WAG but is it possible the intrusion sensors above the centre door pillars do double duty as occupancy sensors? Probably not, but I'd just thought I'd add that to the mix!
If there is a seat sensor I think it must be in the seat back, not in the bottom cushion.
AFAIK on both the 94 MY Sovereign and VDP/Daimler trim levels the seat squab can be removed by taking out the front apron screw and lifting up and forward. Unless I'm mistaken there are no electrical pigtails attached to the squabs?
Our '88 Sovereign and '93 VDP both had electrical connectors for the squabs, but for the '93 I know the only connection was to the seat heating pad. I never took the leather off on our '88.
02-10-2018, 03:05 AM
Seat sensor
